2011-01-27

Spirit Sol 735

Things being in the state they're in, we start the day with an oddly subdued anomaly meeting. Yestersol's drive went OK, with occasional warnings about the dynamic brakes, but since we had disallowed steering on those wheels, there were no resulting faults. The drive terminated after 9m (actually 8.99m, bleah) due to the hazard-avoidance code's decision that there was no safe path behind us. This was really the result of a hair-triggered autonav tilt setting; we're actually quite safe to drive on. Indeed, as one person points out, we're far enough behind the drive metric that driving is the conservative option.

And that's the plan: drive. We might not be able to make that much progress, but at least we'll fall behind our drive metric more slowly this way. (We're about 110m behind now, and roughly 170m from Home Plate.) Due partly to some impassioned pleading on my part, we're going to pack pretty much all of the diagnostics into this sol, so that tomorrow we can plan a normal -- and, I hope, long -- drive for the weekend. Maybe even a pair of drives: we're far enough behind the drive metric that every meter counts, so we might revert to the autonav continuation thing.

John Wright's raring to drive, to the point that I actually have to rein in his enthusiasm a bit. He originally sequences it as a 40m all-blind drive, but I'm uncomfortable with that. The drive sequence is mainly made up of little helpers that check our heading, then take a 60cm step. If we're aimed too far to the left, the step veers a little to the right; if too far to the right, it veers a little to the left; and if we're close enough, it just goes straight.

The problem with this is what happens in the marginal case: you're aimed off course, but not so far that you veer back on course. This keeps you inside a cone centered on the desired heading, but then you have to be sure that the cone doesn't include anything scary. I put together a version of John's sequence that shows the worst case -- what happens if we skate along the extreme left edge of the cone -- and display it on the big projection screen. All kinds of bad stuff is in there -- a sand trap, some big rocks, you name it. He takes one look, hems and haws for a minute, and does the right thing. We scale back to a 23m blind + 15m autonav drive, with tighter limits on the helpers.

Coming back from lunch, I bump into Mark Adler in the elevator. "How'd it go with the Congressman?" he asks.

"Oh, I thought it went pretty well. People seemed to think so."

"Good," he says. "I was talking to Gail Robinson about you." He sees my blank look. "She's Elachi's assistant," he explains. "She was there that day when he brought his tour group through. Yeah, I was talking to her about the Congressman's visit, and she asked me, 'Who was that guy we talked to?' I told her you should do it."

That explains a lot, and is actually pretty close to what I figured. "I wondered what happened with that," I say. "I was like, how would Charles Elachi even know who the hell I am?"